Role of biomedical laboratory testing in detection and
management of disease
Medical laboratory testing has a vital role in the detection
and management of disease in patients. Laboratory tests are used to verify the
presence, magnitude or absence of a disease, the tests are also used to monitor
the effectiveness of a treatment. Laboratory testing includes test results
being analysed, laboratory scientists perform various biological, chemical,
microscopic and bacteriological
tests which require important analytical and independent verdict.
Whole population screening
In medicine screening is used in a population to identify the presence of
an undiagnosed disease in patients who do not demonstrate signs or symptoms. This
could include patients with an unrecognized symptomatic disease.
Blood samples are the most common samples used for
population screening are. It is essential to collect the samples in the easiest
and fastest manner, as this is the best method to analyse the large number of
people. The sample collected then undergoes biomedical laboratory testing.
An example of a screening test is CA-125 blood test, this is
one of the tests used in screening for ovarian cancer in a population. a CA-125
test can be used to identify early signs of ovarian cancer in a group of women
with a high risk of the disease. Once the sample is received in the laboratory,
the test measures the amount of CA-125 in the blood.
diagnosis is the identification of disease or condition by examining the
individual’s symptoms and signs. A diagnosis of a disease is based on
laboratory reports or test results, not just on the physical examination of the
patient. A diagnosis of a diseases requires an examination of the symptoms
displayed, as well as a laboratory attribute of the pathogen involved.
laboratory tests play an important role in detection of
disease, due to their usefulness in diagnosing and managing the most common
diseases and conditions observed in outpatient practice.
Laboratory tests assist in better diagnosis and management
of diseases and conditions seen in patients. Decisions on an individual’s diagnosis, treatment and
monitoring are usually dependent on a range of laboratory-based results.
Blood tests are
an example of laboratory testing, the results are used for diagnosis. At times
a blood disorder may not present any symptoms or signs in a patient, but a
disorder can be later discovered when a laboratory test is done. This shows the
importance of laboratory testing in disease detection.
Disease monitoring is a system which is used to observe the spread of a
disease, it is carried out to establish patterns of progression. An example of
a disease that is monitored is prostate cancer. When a patient is diagnosed
with prostate cancer this does not mean the patient has to immediately undergo
treatment, it is common for doctors to keep an eye on the patient, rather than
starting treatment on the patient straight away. The patient will have regular
tests to examine whether the prostate cancer is remaining in the same place or
beginning to grow. If it is indicated through test results that the cancer is
growing or changing in any way the patient can then begin treatment.
There are 2 techniques used to monitor prostate cancer;
active surveillance and watchful waiting. The method used depends on the individual’s
treatment options, the patient will have active surveillance if the doctor’s
objective is to cure the cancer if it begins to grow. If the patient has
watchful waiting this is due to the doctors aim to control the cancer.
Disease management is a method widely used to teach patients
how to manage their disease. Patients are shown hoe to take responsibility for
understanding how to take good care of themselves. Patients are taught how to
avoid potential problems, and certain actions which can make the disease worse,
of their health problem.
Haematology involves the study of blood and blood diseases, it also focuses
on immunologic, blood clotting and vascular systems. Haematology allows
scientists to better understand many diseases. It involves treating diseases
that affect the production of blood and its elements, for instance blood cells,
haemoglobin, blood proteins, bone marrow, platelets and coagulation.
Complete Blood Count test
A complete blood count is a test that gives a general overview of a patient’s
health. The test is used to acquire the measurements of red blood cells, white
blood cells, haemoglobin, haematocrit and platelets. A complete blood count
reveals any abnormal increases or decreases in cell counts, which calls for
further evaluation as it may indicate a hidden medical condition. The test is
carried out by collecting the blood in a test tube which contains an
anticoagulant to prevent the blood from clotting. In the laboratory the blood is
placed into an analyser, which analyses the different elements in the blood. Within
this test the numbers and types of different cells present in the blood are
counted. The results are then either printed out or sent to a computer for
examination. The reason a complete blood count is carried out for various
reasons such as to review a patient’s overall health, to diagnose a medical
condition, to monitor a medical condition and to monitor a treatment.
Coagulation screening tests
Coagulation tests are used to measure the blood’s ability to clot, and the time
taken for the clot to form. This test assesses any risk of excessive bleeding
or developing clots in your blood vessels as well as identifying any clotting
disorders. Clotting disorders can cause a dangerous amount of bleeding or
clotting. The test is carried out by collecting a blood sample into a bottle
that contains a chemical which stops the blood from clotting. The blood sample
is then analysed in the laboratory. A number of tests are done on the sample
blood, including the ‘prothrombin time’ (PT) and the ‘activated partial
thromboplastin time’ (APTT). PT and APTT measure the time taken for a blood
clot to develop after certain activating chemicals are added into the sample.
If the time taken for a blood clot to form is longer than a normal blood
sample, it is indicated one or more clotting factors are low or not present. The
aim is then to identify which clotting factors these may be.
Microbiology involves the investigation of infectious diseases, microbiology
focuses on specific bacteria, viruses, fungi and parasites that could be
causing a patient symptom. This involves culturing particular bacterium that
imitates a suitable environment for the microorganism, the results are then
examined under a microscope. The sensitivity of the bacteria to antibiotics is
also measure in order to work out treatment.
Blood culture test
Blood cultures tests are commonly used to identify the presence of any bacteria
or fungi within the blood. The test is carried out by collecting blood in two
bottles, an aerobic and anaerobic bottle. In the laboratory the bottles are
placed into a BD Bactec FX, this is where the growth of bacteria is monitored.
If growth is suspected, a gram stain is performed. Gram stain allows better
understanding of the patient’s infection. The test is used to detect the types present,
and to devise the appropriate antimicrobial treatment. It’s vital to test for
blood infections as they can lead to severe complications.
A stool analysis is a series of tests performed on a stool sample, After
the collection of the sample, it is sent to laboratory for testing, in order to
identify the presence or absence of a medical condition. A patent may be
required to provide a stool sample to help diagnose or rule out a particular
health condition. Stools contain the same bacteria and substances present in
the digestive system, by analysing the levels of these substances and bacteria
in your stools, you can work out what’s happening in the digestive system.
Fungal tests are used to detect any fungal infection; the tests determine the
specificity of the fugus present. The fungi may be isolated and grown for
susceptibility testing. Specimens for fungal microscopy and culture may
include; scrapings of skin, hair pulled from the roots, nail clipping, skin
biopsy and a moist swab from a mucosal surface. In the laboratory the fungus is
grown in a culture, incubated at 25-30ºC. The sample collected is inoculated
into a medium. The culture identifies which organism is responsible for the
infection, this test is responsible for finding the source of the infection and
to select a suitable treatment.
Non-biomedical based investigation
Biomedical testing is not the only form of investigation a
patient may undergo. There are various non-biomedical investigations.
Point of care testing
Another form of investigation is point of care testing (POCT), this I
defined as diagnostic testing carried out outside the clinical laboratory, it
can be carried out near the bedside of the patient, at the time and place of
where the patient is receiving care. POCT is usually carried out by
non-laboratory personnel, the results are used to determine treatment.
A diagnostic test is another type of investigation, which is carried out to
confirm the presence of a disease in a patient, this is done by recording
images of the internal structure of the body to identify the presence or
absence of disease, foreign objects, and structural damage or irregularity. This
is an imaging technique used to obtain diagnostic images of the inside of the
body for diagnosis. In medical radiographic testing, radiation is used to provide
images of the tissues, organs, bones, and vessels within the body.
There are several imaging
techniques this includes X-ray radiography, ultrasound, computed tomography
(CT) and magnetic resonance imaging. The detailed images provided by these
imaging techniques can be used to diagnose conditions including problems with
blood flow, strokes and cancer. Using a CT scan also allows the location, size
and shape of a tumour to be determined. This type of investigation is also used
to monitor the condition, this means the size of the tumour can be checked
during and after treatment.
An MRI scanner is a large tube
which consists of powerful magnets. During the scan the patient lies within the
tube. An MRI scan may be used to examine nearly any part of the body. The
results of the scan can be used to aid diagnosis of a condition, results can
also help in developing a plan for treatments.
Electrocardiogram (ECG) Test
An electrocardiogram is a test that measures the electrical activity of the
heart. The electrical activity of the heartbeat is measured. Each beat result
in an electrical impulse traveling through the heart. These electrical impulse
spreads through the walls of the atria and cause them to contract, allowing
blood to pump from the heart. A normal heartbeat on ECG displays timing of the
top and lower chambers.
This test is carried out is to find
out how long it takes for an electrical impulse to travel from part of the
heart to the next, this shows if the electrical activity is regular or not,
whether it is fast or slow. The amount of electrical activity that passes through
the heart can be used to find out if sections of the heart are overworked. The
results from this test are used to see any abnormal or unusual activity.
Different investigations used
to diagnose Liver cancer
Liver function tests
Liver function tests are the most important tests for liver cancer. Liver
function tests help determine the health of the liver, this is done by measuring
the levels of proteins, liver enzymes or bilirubin in your blood.
Liver function tests include alanine transaminase (ALT), aspartate
aminotransferase (AST), alkaline phosphatase (ALP), albumin, and bilirubin
tests. The ALT and AST tests are used to measure the enzymes the liver releases
in response to damage or disease. The albumin and bilirubin tests are used to measure
the livers ability to produce albumin, and the how well the liver disposes of
bilirubin. Liver function tests are very important, as problems with the liver
can be life-threatening.
Urine testing may be carried out if patient complains of kidney problems.
Urine is collected in a container, which is then sent to a laboratory for
testing. Within the laboratory microscopic and chemical tests are performed on
the sample to look for traces of blood and other substances. Urinalysis is
carried out in liver cancer as it can reveal evidence of diseases, including diseases
which have not yet presented any signs or symptoms.
A liver ultrasound scan can also be used to diagnose liver cancer. The
ultrasound scan uses sound waves to produce an image of the liver. The patient
undergoing the test will be lying on their back, the ultrasonographer spreads
gel on the stomach area, a small handheld probe is moved over the area, this
produces sound waves. The sound waves build up a picture of the liver. The ultrasound
images can reveal any cancers growing in the liver.
To confirm the diagnosis of liver cancer, a patient undergoes a tissue
biopsy. During the liver biopsy, part of a mass in the liver is removed by a
surgeon. This is done by passing a fine needle through the skin and taking a
sample of the mass. The sample is then sent to a laboratory where it is
examined under a microscope to determine if the cells present are cancerous.
Computed tomography (CT)
A CT scan can be performed on an individual’s abdomen to look for the
presence of cancer in the liver and elsewhere in that area. The scan can also
be used to detect cancer elsewhere that could have spread to the liver, as well
as determine if the cancer started in the liver or formed in another part of
the body and spread to the liver. A highly detailed picture of the internal
organs is produced by a CT scan, an X-ray machine rotates around the patient’s
body, the patient may be injected with a dye that helps create a clear image of